I'm new to Apache Storm. Currently I'm working on legacy project that involves some streaming processing using Apache Storm. I want to integrate current project with Spring. I found couple comments (Storm and Spring 4 integration, http://mail-archives.apache.org/mod_mbox/storm-user/201605.mbox/%3CCAMwbCdz7myeBs+Z2mZDxWgqBPfjcq-tynOz_+pmPrmY6umfUxA@mail.gmail.com%3E) saying that there are concerns doing that. Can someone explain me how to do such an integration or why it is impossible?
Fair warning, I haven't used Spring in Storm, so this is based solely on my knowledge of Storm, and having used Spring on non-Storm projects, i.e. this is really just guesswork.
I think you can use Spring with Storm, but there are some caveats you should be aware of. Whether Spring is still worth using given these caveats is up to you.
Unlike e.g. a Spring MVC application, Spring will not be responsible for object instantiation or application flow. Storm doesn't know about Spring, and when you run your topology it will be Storm that calls your bolt/spout methods. This means you have to be aware that some parts of your application will be called outside the Spring context.
Here's my guess at where you could use Spring during different phases of a topology deployment.
When you set up your topology and submit it (all your code up to and including StormSubmitter.submitTopology), you can most likely use Spring just like you would in any standalone Java application. e.g. you could start your application like in this example, and put all your submission and wiring code in Main.start. All bolt/spout constructors will run in this phase, so you can use autowiring here if you like. You have to ensure that your spouts and bolts are serializable though.
After topology submission, Storm will serialize your spouts and bolts (and any non-transient fields in these objects), and send them to the supervisor machines, where they will be deserialized. At this point if you need a context available in the worker, you could create one in a worker hook (added to the topology via TopologyBuilder.addWorkerHook), and expose it through a static method on the hook (which is a little ugly, but I don't see any other way to make it available to other parts of the code).
Just to reiterate, if you decide to run a Spring context inside your workers, you have to be aware that the spout/bolt methods will be invoked by Storm outside the Spring context.